Input devices including proximity sensor devices (also commonly called touchpads or touch sensor devices) are widely used in a variety of electronic systems. A proximity sensor device typically includes a sensing region, often demarked by a surface, in which the proximity sensor device determines the presence, location and/or motion of one or more input objects. Proximity sensor devices may be used to provide interfaces for the electronic system. For example, proximity sensor devices are often used as input devices for larger computing systems (such as opaque touchpads integrated in, or peripheral to, notebook or desktop computers). Proximity sensor devices are also often used in smaller computing systems (such as touch screens integrated in cellular phones).
Presently known capacitive sensing devices are limited to accurately detecting input objects that are at or very near the surface. Specifically, most capacitive sensing devices can accurately determine location and/or motion of objects that are either right at the surface, or very near to the surface. However, when the objects are farther away from the surface, detection accuracy degrades, and most devices cannot reliably respond to such objects, and thus simply ignore such objects. This limits the flexibility and usability of the sensor device. Thus, there exists a need for capacitive sensing devices that enhance device flexibility and usability.